Use of alkyl 2,4,6-triisopropylbenzoates in the asymmetric homologation of challenging boronic estersElectronic supplementary information (ESI) available: Full experimental details and characterisation. See DOI: 10.1039/c1cc14469c

(−)-Sparteine induced lithiation of primary 2,4,6-triisopropylbenzoates and subsequent homologation of boronic esters is reported. A comparative study with lithiated N , N -diisopropylcarbamates has demonstrated the superiority of the hindered benzoate. α-Lithiated alkyl 2,4,6-triisopropylbenzoates react with boronic esters to give homologated products. The significant increase in rate of the 1,2-metallate rearrangement compared to carbamates significantly broadens the range of chiral secondary boronic esters that can now be prepared.